1. Field of the Invention
The present invention relates to a printer equipped with a copy function, and more specifically to a printer equipped with a copy function, which printer is suitable for carrying out the two-set double-sided printing.
2. Description of the Related Art
The term “two-set double-sided printing” used herein means that, using a pair of printing papers, each having a printed content, such as characters, figures, photographs or the like on one side thereof, and a blank page on the other side, the printed content on one side of the first printing paper is printed (or copied) on the other side of the second printing paper, and similarly the printed content on one side of the second printing paper is printed (or copied) on the other side of the first printing paper, so that two sets of printing papers, each being printed on both sides, are prepared. The above-mentioned printing paper having a printed content on one side and a blank page on the other side is referred to exclusively as “printing paper” in the specification, and it is discriminated from the other type paper, which is referred to as “paper” or “printing sheet” in the specification.
In carrying out the two-set double-sided printing for many printing papers by the conventional method, using a conventional printer having a copy function, for instance, a first printing paper is placed on a paper feed tray for reading, and the printed content on one side thereof is read out and temporarily stored in storage means. Subsequently, a second printing paper is placed on a paper feed tray for printing in such a manner that the printing can be carried out on the other side of the second printing paper. Thereafter, the printed content of the first printing paper is printed (or copied) on the other side of the second printing paper. Similarly, the second printing paper is placed on the paper feed tray for reading, and the printed content on one side thereof is read out and temporarily stored in storage means. Subsequently, the first printing paper is placed on the paper feed tray for printing in such a manner that the printing can be carried out on the other side of the first printing paper. Thereafter, the printed content on one side of the second printing paper is printed (or copied) on the other side of the first printing paper.
Similarly to the process as for the first and second printing papers, a third and fourth printing papers are treated. In summary, the above-mentioned process is applied to each pair of two adjacent printing papers to print or copy the printed content on one side of each printing paper onto the other side thereof. This procedure permits the two-set double-sided printing for many printing papers each having a printed content on one side and a blank page on the other side, thereby enabling the sheets of printing paper to be saved.
In the case when the two-set double-sided printing is carried out with the aid of the above procedure, a user has to stack the printing papers either on the paper feed tray for reading or the paper feed tray for printing, while always directing his attention to the reading sequence of the printing papers as well as to the side to be printed for the printing papers. Such a complicated procedure makes it difficult to perform an actual printing process, in particular with an increase in the number of printing papers.
In the related art disclosed in Japanese Examined Patent Japanese Patent Laid-Open No. 11-020272, each printed content on one side of all the printing sheets is read in, the printed content thus read in odd-numbered printing sheets is printed on the other side of even-numbered printing sheets respectively, and the printed content thus read in even numbered printing sheets is printed on the other side of odd-numbered printing sheets respectively. In this case, however, the printing sheets have blank pages on both sides without any printed content. It can be stated, therefore, that this printing process does not pertain to the two-set double-sided printing where the printing content on one side of a printing paper is printed or copied on the other side of the following printing paper, thereby making it impossible to sufficiently save the number of printing sheets.